Control device



' CONTROL DEVICE Filed Fb. 15. 1943 Zinnentor Gttorng.

w. A. RAY 2,409,337

Patented Oct. 15, 1946 CONTROL DEVICE William A. Ray, Los Angeles,Calif., assignor to General Controls 00., a corporation ApplicationFebruary 15, 1943, Serial No. 475,859

3 Claims.

My present invention relates to condition-responsive control devices,such as thermostats, pressurestats, or the like, and has for an objectthe provision of a pair of such devices, mounted one upon, the other,having unitary means for connecting the respective devices to apparttusto .be controlled by them. This application is a continuation-in-part ofmy copending application, Serial No. 385,719, filed March 28, 1941.

Another object is to provide an arrangement, of the character describedin the preceding object, wherein one of the devices has a portionextended for connection to a relatively remote apparatus to becontrolled, such as a valve or switch; the other of the devices being ofthe electric-circuit-controlling type and having electrical conductingmeans which forms a unitary part of the extended portion of thefirst-mentioned' device.

A more specific object is to provide an arrangement, of the characterdescribed in the preceding object, wherein one of the devices is of thetemperature responsive type and comprises a thermal bulb having acapillary tube portion extended for connection to relatively remotefluid pressure operated means to be controlled; the other of thedevices, of the electric-circuit-controlling type, having conductingmeans which forms a unitary part of the capillary tube of thefirstmentioned device.

Another object is to provide, in an arrangement of the characterdescribed in the preceding objects, means for automatically connectingthe electric-circuit-controlling device to the conducting means uponmounting of the devices one upon the other. By providing (1) conductingmeans for the electrical device, which means forms a unitary part of theextended portion or capillary tube of the other device, and (2) meansfor automatically connecting and disconnecting the electrical device toand from the conducting means when the devices are respectively unitedor separated-the possibility of failure of the installer to make orbreak such connection is obviated. This is of particular importance whenthe electrical device is of the normally closedcircuit type and isemployed as a safety or highlimit control, and hence failure to breakthe connection upon removal of the other device would permit theestablishment of an unsafe condition. Likewise, if the electrical deviceis of the normally open-circuit type, failure to make the connectionwhen the devices are assembled would not be apparent under normalconditions of operation, even although the electrical device would thenbe inoperative.

Other objects and advantages of the invention will be' found in thedescription, the drawing, and the claims; and, for full understandin ofthe invention, reference may be had to the following detaileddescription and accompanying drawing, wherein:

Figure 1 is a lo-ngtiudinal'sectional view of condition-responsiveapparatus embodying my invention shown by way of example, connected tocontrol the operation of a gas heating system illustrated in diagram;and I Figure 2 is a fragmentary transverse section taken along the line22 of Fig. 1.

Referrin first to the burner control system shown in the lower portionof Fig. 1, the numeral ll indicates a main' burner which is connected bya conduit I2 to the outlet l3 of ,a fluid pressure operated valvegenerally indicated at I4. Connected in series with and ahead of valveI4 is another valve [5 of the rotary plug type, to the inlet of which isconnected an electromagnetically controlled safety valve generallyindicated at 16.

The valve 14 comprises a casing ll having an opening in its top wallwhich is closed by a flexible diaphragm l8. Securing the diaphagm to thecasing, and providing a pressure chamber thereabove, is a housing I9.Extending from a pressure plate 20, secured to the underside of thediaphragm, is a stem 2| which is pivoted at its lower end on anintermediate portion of an arm 22. This arm is pivotally mounted at oneof its ends on a pin 23 secured to the casing. Pivotally connected toanother intermediate portion of arm 22 is a stem 24 for a closure member25, which closure member is cooperable with a Valve seat 26 provided inthe bottom wall of the casing. A spring 21, compressed between a sidewall of the casing and the free end of arm 22, is arranged to efiectsnap-action of the closure member in its opening and closing movementsas arm 22 moves past center. So that this snap-action may be fullyeffective, the upper and lower portions of stem 2| are interconnected bya lost-motion device 49. Urging the diaphragm and the closure memberupward, is a compression spring 28.

The safety valve It comprises a casing 29 having a ported partition 3tproviding a valve seat 31. Cooperable with this seat is a closure member32 mounted on a rod 33, the free end of which sealingly extends througha side wall of the easing and is provided at its outer end with acompression spring 34 which urges the closure mem- 3 her 32 toward itsseat. Mounted in the safety valve casing 29 is an electromagnet 35comprising a U-shaped core 36 which carries on one of its arms anenergizing coil 31.

Mounted on the stem 38 of the plug valve is a cam 39 which, in therotation of the plug valve, is adapted to engage the outer end of rod 33and thereby move the closure member 32 away from its seat and intoengagement with the pole faces of the electromagnet core 35. The closuremember 32 is constructed wholly or in part of magnetic material so thatwhen it is brought into engagement with the core, while the same isenergized by passage of current through coil 31, the closure member willbe magnetically retained in open position against the bias of spring 34.The electromagnet 35 is so designed that the closure member ismagnetically held only when it is first brought into engagement with thecore, no attraction of the closure member through space beingcontemplated. It will be noted that the cam 39 is so arranged withrespect to the plug valve that the same is closed when the safety valveclosure member is moved to its open position. The general combination ofplug valve and safety valve, shown herein, is disclosed in Patent No.2,297,718 granted to me October 6, 1942.

Referring now to the upper portion of Fig. 1 and to Fig. 2, there isshown, mounted in a wall of a boiler 46 heated by the main burner H, acombination thermostatic control device which comprises a cylindricalthermal bulb 41 and a bimetallic member 48. The thermal bulb is mountedin the boiler by means of a fitting 49 threaded in a nipple 50 welded inan opening through the boiler wall; a gland nut 5|, threaded in theouter end of the fitting and closely surrounding the bulb, beingprovided for the compression of packing material 52 which serves tosealingly hold the bulb in position. The thermal bulb, the outer end ofwhich is fluidly connected by a capillary tube 53 to the valve housingI9, is of conventional type, being of metal of high thermal conductivityand containing a volatile fluid which, upon predetermined rise oftemperature of the boiler water, expands and thus produces a pressurewithin housing l9 above the diaphragm is suiiicient to move the samedownward against the bias of spring 28 so that the closure member 25 isbrought into engagement with its seat.

The bimetallic member 48 is curved on an are substantially concentricwith the thermal bulb and is secured at one end to a boss 54 provided onthe outer end portion of the fitting 49 so that it is in goodheat-transfer relation to the bulb the fitting 49 being of materialhaving high thermal conductivity, such as brass. Insulatingly secured tothe free end of the bimetallic member is a short metallic strip 55 whichcarries an adjustable contact screw 5'5 cooperable with a fixed contactmember 51 secured to another boss 58 formed on the outer end portion offitting 49; the contacts 56 and 51 being in continuous engagement undernormal conditions. The contact screw 56 is electrically connected by thestrip 55 and a wire 59 to a female electrical connector 60 insulatinglymounted on the flange portion of fitting 49; a similar female connector6|, mounted directly on an adjacent portion of the fitting flange,serving as electrical connecting means for the grounded contact member51. Enclosing the bimetallic member is a cap 62 which is attached to thefitting 49 by three screws 53.

Around the capillary tube 53 of the thermal bulb 41 is electricalconducting means comprising a sleeve 84 of woven wire which iselectrically insulated from the capillary tube by a sleeve 65 of rubberor other suitable material. Molded on the outer end portion of thethermal bulb, and surrounding the adjacent end of the capillary tube, isa head 65 of insulating material such as Bakelite. Carried by this headis a pair of connector pins 51 which are cooperable respectively withthe female connectors and Bi and extend through suitable openings in cap62; the pin which cooperates with the insulated connector So beingconnected by a wire 68 to the conducting sleeve 64, the other pin whichcooperates with the grounded connector 6| being connected by a wire 69to the capillary tube 53. By the arrangement described, the thermostaticcontrol device constituted by the bimetallic member 48 is automaticallyconnected to the conducting means, comprising sleeve 64 and capillarytube 53, when the thermal bulb is mounted on the fitting 43.

For the energization of the electromagnet 35, there is provided athermoelectric generating device 10 comprising a pair, or plurality ofpairs, of thermocouple elements contained within a protecting sleeve 1|.The upper, or hot junction end of this device is arranged to be heatedby the flame of a pilot burner 12 mounted on the main burner ll, for theignition of which it also serves; the pilot burner being connected by apipe 11 to the outlet of the safety valv (6. One lead of thethermoelectric generating device is connected by a wire 13 directly toone terminal of the electromagnet coil 31; the other lead of the devicebeing connected by a clamp 14 to the capillary tube 53, and the otherterminal of the coil by a wire 15 and clamp 16 to the conducting sleeve64. By these connections, the energizing circuit of the electromagnet isplaced in series with the contact members 56-51 of the bimetallicthermostatic device, these members being in continuou engagement at allnormal operating temperatures of the boiler.

With the parts in the positions shown in the drawing, fuel supply toboth the main burner H and the pilot burner 12 is obstructed by thesafety valve closure member 32. To initiate operation of the system, theplug valve 15 is rotated from its open position, as shown, to a closedposition wherein engagement of cam 39 with the end of rod 33 movesclosure m mber 32 away from its seat and into engagement with the polefaces of core 36, whereupon fuel can fiow through pipe 11 to the pilotburner 12 where it is lighted. The plug valv is manually retained insafetyvalve-opening position until the thermoelectric device 19 hasbecom sufficiently heated by the pilot burner flame to generate currentin an amount sufficient to cause the electromagnet to hold thearmature-closure member 32 in the position shown by the broken lines,When this occurs, the plug valve may be returned to its open position,fuel then passing to th automatic valve i4 which, if the water in theboiler is relatively cold, will b open position on account of thecontraction of the fluid in the thermal bulb 41. Fuel can therefore thenflow to the main burner H where it is ignited by the pilot burner flame.When the temperature of the boiler water reaches a predetermined degree,the pressure of the fluid in the thermal bulb, applied to the diaphragml3, effects closure of the automatic valve and hence extinguishment ofthe main burner. Upon resultant cooling of the water, the automaticvalve reopens under the force of spring 28 due to reduction of fluidpressure above the diaphragm; recycling of the valve maintaining thetemperature of the water between predetermined limits.

If, due to faulty operation of the automatic valve or its control means,or from other causes, the temperature of the water rises to an abnormaldegree, resultant outward warping of the bimetallic member 48 effectsdisengagement of the contact. members 5651 and thereby deenergization ofelectromagnet 35. The safety valve closure member 32 is thus permittedto return to its seat under the force of sprin 34. Fuel flow to both themain and the pilot burner is therefore obstructed and the system must bemanually reset as described above in order to reinitiate operation afterthe cause of the failure has been corrected. The bimetallic member,being in intimate thermal contact with the fitting 49 and insulated fromthe surrounding atmosphere by the cap 62, is at all times substantiallyat the temperature of the boiler water. By the angular arrangement ofcontact member 51, a wiping action occurs in the relative movement ofthe contacts.

An additional safety feature is provided by the pilot-burner-heatedthermoelectric generating device. If the pilot burner should beaccidentally extinguished, upon cooling of the thermo-electric devicethe resultant cessation of current generation effects deenergization ofthe electromagnet and the safety valve closes.

If for some reason the thermal bulb is removed from the fitting, theelectrical circuit of the bimetallic thermostatic device isautomatically broken, thereby effecting release of the safety valveclosure member 32 to closed position. If such au-, tomatic disconnectingmeans were not provided, and if one were to fail to break the circuit ofthe safety valve in some other way, upon cooling of the thermal bulb thevalve 14 would open and heat would be supplied to the boiler, with thepossibility that the same would be damaged, since the water would thenbe below the level of the thermostat fitting. This safety feature of theinvention does not depend entirely upon the provision of the separableconnectors 606| and 61, since, if manually connectible means, extendingbetween the bimetallic unit and the conductor means 64, 53, weresubstituted therefor, these connections would have to be broken in orderto remove the thermal bulb. Obviously, other means could be provided foreiiecting the safety disconnection, such as for instance means carriedby the thermal bulb and cooperating mechanically with the bimetallicmember.

While I have herein shown and described a specific embodiment of myinvention, I wish it to be understood that modifications may be madewithout departing from the spirit of the invention, and that I intendtherefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In combination: a first temperature-responsive control devicecomprising a thermal bulb having a metallic capillary tube extendingtherefrom for connection to relatively remote fluid pressure operatedmeans to be controlled by the device, a second temperature-responsivedevice adapted to control an electric circuit and mounted on saidthermal bulb in good heat-transfer relation thereto so that both of saiddevices are substantially equally thermally affected, and a pair ofelectrical conductors for connecting said second device in said circuit,one of said electrical conductors being formed in part by said capillarytube and the other comprising an element insulatingly supported by thetube.

2. The combination defined in claim 1 wherein said other of saidelectrical conductors comprises conductive material encircling saidcapillary tube and electrically insulated therefrom.

3. The combination defined in claim 1 wherein said other of saidelectrical conductors comprises a sleeve of woven wire encircling saidcapillary tube and electrically insulated therefrom.

WILLIAM A. RAY.

